Compositions and use of compositions in printing processes

ABSTRACT

An aqueous sacrificial coating composition for an image transfer member in an aqueous ink imaging system is provided. The sacrificial coating composition may include at least one polymer, at least one selected from (i) at least one chain extender, or (ii) a reactive elastomeric latex, wherein the at least one chain extender comprises a species capable of linking linear chains or chain segments of the reactive elastomeric latex, at least one hygroscopic plasticizer, and at least one surfactant.

DETAILED DESCRIPTION Field of the Disclosure

This disclosure relates generally to indirect inkjet printers, and inparticular, to a sacrificial coating employed on an intermediatetransfer member of an inkjet printer and a method of depositing asacrificial coating.

Background

In aqueous ink indirect printing, an aqueous ink is jetted onto anintermediate imaging surface, which can be in the form of a blanket. Theink is partially dried on the blanket prior to transfixing the image toa media substrate, such as a sheet of paper. To ensure excellent printquality it is desirable that the ink drops jetted onto the blanketspread and become well-coalesced prior to drying. Otherwise, the inkimages appear grainy and have deletions. Lack of spreading can alsocause missing or failed inkjets in the printheads to produce streaks inthe ink image. Spreading of aqueous ink is facilitated by materialshaving a high energy surface.

In order to facilitate transfer of the ink image from the blanket to themedia substrate after the ink is dried on the intermediate imagingsurface, a blanket having a surface with a relatively low surface energyis preferred. Rather than providing the desired spreading of ink, lowsurface energy materials tend to promote “beading” of individual inkdrops on the image receiving surface.

An optimum blanket for an indirect image transfer process must tackleboth the challenges of wet image quality, including desired spreadingand coalescing of the wet ink; and the image transfer of the dried ink.The first challenge—wet image quality—prefers a high surface energyblanket that causes the aqueous ink to spread and wet the surface. Thesecond challenge—image transfer—prefers a low surface energy blanket sothat the ink, once partially dried, has minimal attraction to theblanket surface and can be transferred to the media substrate.

Various approaches have been investigated to provide a solution thatbalances the above challenges. These approaches include blanket materialselection, ink design and auxiliary fluid methods. With respect tomaterial selection, materials that are known to provide optimum releaseproperties include the classes of silicone, fluorosilicone, afluoropolymer such as TEFLON or VITON, and certain hybrid materials.These materials have low surface energy, but provide poor wetting.Alternatively, polyurethane and polyimide have been used to improvewetting, but at the cost of ink release properties.

Tuning ink compositions to address these challenges has proven to bedifficult since the primary performance attribute of the ink is theperformance in the print head. For instance, if the ink surface tensionis too high it will not jet properly and it if is too low it will droolout of the face plate of the print head. Additional attempts at solvingthe above challenges have included applying a sacrificial wettingenhancement starch coating onto the blanket to improve wetting andspread of ink while maintaining transfer capabilities.

Identifying and developing new polymers that improve wet image qualityand/or image transfer and methods of depositing such polymers would beconsidered a welcome advance in the art.

SUMMARY

In an embodiment there is an aqueous sacrificial coating composition foran image transfer member in an aqueous ink imaging system. Thesacrificial coating composition may include at least one polymer, atleast one selected from (i) at least one chain extender, or (ii) areactive elastomeric latex, wherein the at least one chain extendercomprises a species capable of linking linear chains or chain segmentsof the reactive elastomeric latex, at least one hygroscopic plasticizer,and at least one surfactant.

In another embodiment there is an ink composition. The ink compositioncan include a latex emulsion, a reactive elastomeric latex capable ofreacting with a chain extender, at least one colorant, and at least onesolvent.

In yet another embodiment there is an indirect printing process. Theprocess can include forming a liquid sacrificial coating compositionlayer by applying one or more components of a sacrificial coatingcomposition onto an intermediate transfer member of a printingapparatus. The printing process can include forming a sacrificialcoating by at least partially drying the liquid sacrificial coatingcomposition, optionally, forming a partially cured sacrificial coatingby activating a chain extender of the liquid sacrificial coatingcomposition to at least partially cure the sacrificial coating, ejectingdroplets of an ink composition in an imagewise pattern onto thepartially dried sacrificial coating or partially cured sacrificialcoating, processing the ink to form an ink pattern on the intermediatetransfer member, wherein processing comprises activating the chainextender to react with the reactive elastomeric latex and substantiallydrying the ink composition, and transferring both the ink pattern andthe sacrificial coating from the intermediate transfer member to a finalsubstrate. The one or more components of the sacrificial coatingcomposition may be selected from the group consisting of at least onepolymer, at least one chain extender, wherein the at least one chainextender comprises a species capable of linking linear chains or chainsegments of the reactive elastomeric latex, at least one hygroscopicplasticizer; and at least one surfactant. The ink composition mayinclude a latex emulsion and a reactive elastomeric latex capable ofreacting with the chain extender.

Embodiments of the present disclosure can provide one or more of thefollowing advantages: coatings having good wettability, coatings havinggood ink wetting and ink spreading, image transfer member coatingsexhibiting improved wet image quality and/or improved image transferwith aqueous inks, improved physical robustness or increased shelf life.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory onlyand are not restrictive of the present teachings, as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate embodiments of the presentteachings and together with the description, serve to explain theprinciples of the present teachings.

FIG. 1 is a schematic drawing of an aqueous indirect inkjet printer thatprints sheet media, according to an embodiment of the presentdisclosure.

FIG. 2A is a schematic drawing of a surface maintenance unit thatapplies a sacrificial coating composition onto a surface of anintermediate transfer member in an inkjet printer, according to anembodiment of the present disclosure.

FIG. 2B is a schematic drawing of a surface maintenance unit thatincludes an applicator for applying at least some components to form afirst portion of a sacrificial coating composition onto a surface of anintermediate transfer member in an inkjet printer and acatalyst-delivery printhead for ejecting droplets of catalyst onto thefirst portion of the sacrificial coating

FIG. 3A is a block diagram of a process for printed images in anindirect inkjet printer that uses aqueous inks, according to anembodiment of the present disclosure.

FIG. 3B is a block diagram of a process for printed images in anindirect inkjet printer that uses aqueous inks, according to anembodiment of the present disclosure.

FIG. 4A is a side view of a sacrificial coating composition that isformed on the surface of an intermediate transfer member in an inkjetprinter, according to an embodiment of the present disclosure.

FIG. 4B is a side view of dried hydrophilic composition on the surfaceof the intermediate transfer member after a dryer removes a portion of aliquid carrier in the hydrophilic composition, according to anembodiment of the present disclosure.

FIG. 4C is a side view of a portion of an aqueous ink image that isformed on the dried hydrophilic composition on the surface of theintermediate transfer member, according to an embodiment of the presentdisclosure.

FIG. 4D is a side view of a portion of the aqueous ink image that isformed on the dried hydrophilic composition after a dryer in the printerremoves a portion of the water in the aqueous ink, according to anembodiment of the present disclosure.

FIG. 4E is a side view of a print medium that receives the aqueous inkimage and a portion of the dried layer of the hydrophilic compositionafter a transfix operation in the inkjet printer, according to anembodiment of the present disclosure.

FIGS. 5A-5C are microscope images showing film-forming property ofvarious coating compositions as deposited on a blanket substrates andthen dried as described in the examples below.

It should be noted that some details of the figure have been simplifiedand are drawn to facilitate understanding of the embodiments rather thanto maintain strict structural accuracy, detail, and scale.

DESCRIPTION OF THE EMBODIMENTS

Reference will now be made in detail to embodiments of the presentteachings, examples of which are illustrated in the accompanyingdrawings. In the drawings, like reference numerals have been usedthroughout to designate identical elements. In the followingdescription, reference is made to the accompanying drawing that forms apart thereof, and in which is shown by way of illustration a specificexemplary embodiment in which the present teachings may be practiced.The following description is, therefore, merely exemplary.

As used herein, the terms “printer,” “printing device,” or “imagingdevice” generally refer to a device that produces an image on printmedia with aqueous ink and may encompass any such apparatus, such as adigital copier, bookmaking machine, facsimile machine, multi-functionmachine, or the like, which generates printed images for any purpose.Image data generally include information in electronic form which arerendered and used to operate the inkjet ejectors to form an ink image onthe print media. These data can include text, graphics, pictures, andthe like. The operation of producing images with colorants on printmedia, for example, graphics, text, photographs, and the like, isgenerally referred to herein as printing or marking. Aqueous inkjetprinters use inks that have a high percentage of water relative to theamount of colorant and/or solvent in the ink.

The term “printhead” as used herein refers to a component in the printerthat is configured with inkjet ejectors to eject ink drops onto an imagereceiving surface. A typical printhead includes a plurality of inkjetejectors that eject ink drops of one or more ink colors onto the imagereceiving surface in response to firing signals that operate actuatorsin the inkjet ejectors. The inkjets are arranged in an array of one ormore rows and columns. In some embodiments, the inkjets are arranged instaggered diagonal rows across a face of the printhead. Various printerembodiments include one or more printheads that form ink images on animage receiving surface. Some printer embodiments include a plurality ofprintheads arranged in a print zone. An image receiving surface, such asan intermediate imaging surface, moves past the printheads in a processdirection through the print zone. The inkjets in the printheads ejectink drops in rows in a cross-process direction, which is perpendicularto the process direction across the image receiving surface.

As used in this document, the term “aqueous ink” includes liquid inks inwhich colorant is in a solution, suspension or dispersion with a liquidsolvent that includes water and/or one or more liquid solvents. Theterms “liquid solvent” or more simply “solvent” are used broadly toinclude compounds that may dissolve colorants into a solution, or thatmay be a liquid that holds particles of colorant in a suspension ordispersion without dissolving the colorant. Various components can beincluded in an aqueous ink composition as described further below.

As used herein, the term “hydrophilic” refers to any composition orcompound that attracts water molecules or other solvents used in aqueousink. As used herein, a reference to a hydrophilic composition refers toa liquid carrier that carries a hydrophilic agent. Examples of liquidcarriers include, but are not limited to, a liquid, such as water oralcohol, that carries a dispersion, suspension, or solution.

As used herein, the term “crosslinker” refers to low-molecularmultifunctional species that can modify physical properties ofcompositions of monomers, prepolymers or macromolecules. For example, asis understood in the art, “crosslinker” may refer to difunctional (f=2)species (also known as “chain extenders”) that link linear chains orchain segments to obtain higher molecular weight linear macromolecules,as well as tri-functional (f=3) or multifunctional (f>3) species thatlink linear chains or chain segments to obtain tridimensionalmacromolecules of higher crosslinking density.

As used herein, a reference to a dried layer or dried coating refers toan arrangement of a liquid composition after all or a substantialportion of the liquid carrier has been removed from the compositionthrough a drying process and/or the arrangement of a cured liquidcomposition. As described in more detail below, an indirect inkjetprinter forms a layer of a sacrificial coating composition on a surfaceof an intermediate transfer member using a liquid carrier, such aswater, to apply a layer of the sacrificial coating composition. Theliquid carrier is used as a mechanism to convey the sacrificial coatingcomposition to an image receiving surface to form a uniform layer, suchas a sacrificial coating, on the image receiving surface.

An embodiment of the present disclosure is directed to an aqueoussacrificial coating composition for an image transfer member in anaqueous ink imaging system. Through appropriate selection of componentsfor each of an ink composition and/or sacrificial coating composition,controlled transfer of image from the intermediate substrate to thefinal substrate may be achieved. In an embodiment, a reactiveelastomeric latex is included in an ink composition, for example, as ablend with a conventional latex. A cross linker or chain extender in thesacrificial coating composition that may be activated to partially curethe film during a drying process may be selected, for example, topartially cure the composition enough for the image to achieveappropriate transfer rheology. In an example, the crosslinker or chainextender can be digitally added to the partially dried sacrificial, forexample as droplets ejected from an inkjet printhead.

The sacrificial coating composition may include at least one polymer, atleast one selected from (i) at least one cross linker, such as a chainextender, or (ii) a reactive elastomeric latex, wherein the at least onechain extender comprises a species capable of linking linear chains orchain segments of the reactive elastomeric latex, at least onehygroscopic plasticizer, and at least one surfactant.

The at least one polymer may be at least one hydrophilic polymer. The atleast one hydrophilic polymer may be selected from the group consistingof starch, polyvinyl alcohol (PVOH), copolymers of PVOH,poly(vinylpyrrolidinone) (PVP), poly(ethylene oxide), hydroxyethylcellulose, cellulose acetate, poly(ethylene glycol), poly(ethyleneglycol), copolymers of poly(ethylene glycol), diblock copolymers ofpoly(ethylene glycol), triblock copolymers of poly(ethylene glycol),polyacrylamide (PAM), poly(N-isopropylacrylamide) (PNIPAM), poly(acrylicacid), polymethacrylate, acrylic polymers, maleic anhydride copolymers,sulfonated polyesters, and mixtures thereof. The at least onehydrophilic polymer can have suitable weight average molecular weightfrom 3000 to 300,000. In an embodiment, the at least one hydrophilicpolymer can provide a suitable viscosity for forming a sacrificialcoating on an intermediate transfer member. For example, at about 5% byweight of the at least one hydrophilic polymer in a solution DI water,at 20° C. the viscosity can range from about 2 cps to about 800 cps,such as about 3 cps to about 500 cps, or about cps to about 100 cps,where the % by weight is relative to the total weight of the at leastone hydrophilic polymer and water. The at least one hydrophilic polymermay have excellent wet film-forming and good water retention propertieswhich can assist the ink spreading on the blanket, and can have uniformfilm-forming properties, for example, after the liquid coatingcomposition is semi-dried or dried on a substrate. The at least onehydrophilic polymer may have 100% solubility in water or hydrophilicmedia.

In an embodiment, the at least one polymer may include one or morerepeating polymeric units selected from the group consisting of alkylacrylate, styrene and butadiene, isoprene, methacrylonitrile,acrylonitrile, vinyl ethers, vinyl esters, vinyl ketones, vinylidenehalide, N-vinyl indole, N-vinyl pyrrolidene, acrylic acid, methacrylicacid, acrylamide, methacrylamide, vinylpyridine, vinylpyrrolidone,vinyl-N-methylpyridinium chloride, vinyl naphthalene, p-chlorostyrene,vinyl chloride, vinyl bromide, vinyl fluoride, ethylene, propylene,butylene, isobutylene, and mixtures thereof.

The at least one crosslinker may include at least one of a difunctional(such as a chain extender), trifunctional or multifunctional compound.Thus, the at least one crosslinker or chain extender may include ahydroxyl terminated compound, an amine terminated compound, or mixturesthereof. For example, hydroxyl compounds usable as crosslinkers or chainextenders may be difunctional ones selected from ethylene glycol,diethylene glycol, triethylene glycol, tetraethylene glycol, propyleneglycol, dipropylene glycol, tripopylene glycol, 1,3-propanediol,1,3-butanediol, 1,4-butanediol, neopentyl glycol, 1,6-heanediol,1,4-cyclohexanedimethanol, hydroquinone Bis(2-hydroxyethyl)ether (HQEE),ethanolamine, diethanolamine, methyldiethanolamine, andphenyldiethanolamine. Hydroxyl compounds usable as crosslinkers may alsobe trifunctional ones selected from glycerol, trimethylolpropane,1,2,6-hexanetriol, and triethanolamine. Hydroxyl compounds usable ascrosslinkers may be tetrafunctional ones selected from pentaerythritol,and N,N,N′,N′-tetrakis(2-hdroxypropyl)ethylenediamine. Amine compoundsusable as crosslinkers may be difunctional ones selected fromdiethyltoluenediamine, and dimethylthiotoluenediamine. Additionally, thecrosslinker may be selected from 1,4,-Bis(2-hydroxyethoxy)benzene(BHEB). In an embodiment, a weight percentage of the crosslinker may bebetween about 0 wt and about 10 wt %, for example 0.1 wt % to about 10wt %, such as greater than 0 wt % and less than about 4 wt %.

The reactive elastomeric latex may be a polyurethane elastomer, forexample, a water-based aliphatic polyurethane elastomer such asPRECIDIUM™ Aqua 90A (available from Quantum Chemical, Alberta, Canada).Accordingly, the crosslinker may be any material that can crosslink withthe polyurethane elastomer.

The polymer-containing sacrificial coating of the embodiments can betailored to fine-tune the wettability and release characteristics of thesacrificial coating from the underlying ITM surface. This can beaccomplished, in part, by employing one or more hygroscopic materialsand one or more surfactants in the sacrificial coating composition. Anysuitable hygroscopic material can be employed. For example, thehygroscopic material can be functionalized as a plasticizer.Accordingly, as used herein, the term “hygroscopic plasticizer” refersto a hygroscopic material that has been functionalized and can becharacterized as a plasticizer. In an embodiment, the at least onehygroscopic material is selected from the group consisting ofglycerol/glycerin, sorbitol, xylitol, maltito, polymeric polyols such aspolydextrose, glyceryl triacetate, vinyl alcohol, glycols such aspropylene glycol, hexylene glycol, butylene glycol, urea, alpha-hydroxyacids (AHA's). A single hygroscopic material can be used. Alternatively,multiple hygroscopic materials, such as two, three or more hygroscopicmaterials, can be used.

Any suitable surfactants can be employed. Examples of suitablesurfactants include anionic surfactants, cationic surfactants, non-ionicsurfactants such as TERGITOL™ TMN-6 (available from The Dow ChemicalCompany, Midland, Mich.) and mixtures thereof. The non-ionic surfactantscan have an HLB value ranging from about 4 to about 14. A singlesurfactant can be used. Alternatively, multiple surfactants, such astwo, three or more surfactants, can be used. For example, a mixture of anon-ionic surfactant with a low HLB value from about 4 to about 8, and ahigh HLB non-ionic surfactant with value from about 10 to about 14demonstrates good wetting performance.

Initially, the sacrificial coating composition is applied to theintermediate transfer member (“ITM”), where it is semi-dried or dried toform a film, such as a sacrificial coating. The sacrificial coating canhave a higher surface energy and/or be more hydrophilic than the baseITM, which is usually a material with low surface free energy, such as,for example, a polysiloxane, such as polydimethylsiloxane or othersilicone rubber material, fluorosilicone, TEFLON, polyimide orcombinations thereof.

In an embodiment, the sacrificial coating composition is made by mixingthe ingredients comprising: at least one polymer, at least onehygroscopic plasticizer; at least one surfactant and water. Thesacrificial coating composition can further be made by mixing, inaddition to the above ingredients, at least one selected from (i) atleast one crosslinker, such as a chain extender, or (ii) the reactiveelastomeric latex. These ingredients can be mixed in any suitable mannerto form a sacrificial coating composition that can be coated onto theintermediate transfer member. The sacrificial coating composition mayhave a pH of from about 5 pH to about 10 pH. In addition to theingredients discussed above, the mixture can include other ingredients,such as solvents and biocides. Example biocides include ACTICIDES® CT,ACTICIDES® LA 1209 and ACTICIDES® MBS in any suitable concentration,such as from about 0.1 weight percent to about 2 weight percent.Examples of suitable solvents include water, isopropanol, MEK (methylethyl ketone) and mixtures thereof.

The ingredients of the sacrificial coating composition may be mixed inany suitable amounts. For example, the at least one hydrophilic polymermay be added in an amount of from about 0.5 wt % to about 30 wt %, orfrom about 1 wt % to about 10 wt %, or from about 1.5 wt % to about 5 wt% based upon the total weight of the sacrificial coating composition.The at least one surfactant may be present in an amount of from about0.1 wt % to about 4 wt %, or from about 0.3 wt % to about 2 wt %, orfrom about 0.5 wt % to about 1 wt %, based upon the total weight of thesacrificial coating composition. The at least one hygroscopicplasticizer may be present in an amount of from about 0.5 wt % to about30 wt %, or from about 5 wt % to about 20 wt %, or from about 10 wt % toabout 15 wt %, based upon the total weight of the sacrificial coatingcomposition. The at least one reactive elastomeric latex may be presentin an amount of from greater than 0 wt % to about 10 wt %, for exampleless than or equal to about 3 wt %, based upon the total weight of thesacrificial coating composition. The crosslinker, for example, the chainextender, may be present in an amount of from greater than 0 wt % toabout 10 wt %, for example, from about 0.1 wt % to about 10 wt %, suchas, greater than 0%, based upon the total weight of the sacrificialcoating composition.

The sacrificial coating composition can be applied over the substrate byany suitable method including, but not limited to, dip coating, spraycoating, spin coating, flow coating, stamp printing, die extrusioncoatings, flexo and gravure coating and/or blade techniques In exemplaryembodiments, an air atomization device such as an air brush or anautomated air/liquid spray can be used for spray coating. In anotherexample, a programmable dispenser can be used to apply the coatingmaterial to conduct a flow coating.

In embodiments, the sacrificial coating composition can first be appliedor disposed as a wet coating on the intermediate transfer member. Adrying or curing process can then be employed. In embodiments, the wetcoating can be heated at an appropriate temperature for the drying andcuring, depending on the material or process used. For example, the wetsacrificial coating composition can be heated to a temperature rangingfrom about 30° C. to about 200° C. for about 0.01 to about 100 secondsor from about 0.1 second to about 60 seconds. In embodiments, after thedrying and curing process, the sacrificial coating can have a thicknessranging from about 0.02 micrometer to about 10 micrometers, or fromabout 0.02 micrometer to about 5 micrometers, or from about 0.05micrometer to about 1 micrometers. Depending on the temperature and timeselected for heating the deposited sacrificial coating composition, asacrificial coating may form via partial drying and the crosslinker, forexample, the chain extender, may be activated to partially cure thesacrificial coating.

In an embodiment, the sacrificial coating can cover a portion of a majorsurface of the intermediate transfer member. The major outer surface ofthe intermediate transfer member can comprise, for example, polysiloxaneand/or a fluorinated polymer.

It has been found that the sacrificial coating overcomes the wet imagequality problem discussed above by providing an ink wetting surface onthe intermediate transfer member. The coatings may also improve theimage cohesion significantly to enable excellent image transfer.

An embodiment of the present disclosure also includes the deposition ofan ink composition, for example, an aqueous latex ink composition, ontothe sacrificial coating. The ink composition can be a reactive inkcomposition, for example, an ink composition that includes a componentthat reacts with a component of the underlying sacrificial coating. Inan embodiment, the ink composition can include a latex emulsion and areactive elastomeric latex capable of reacting, for example, reactingwith a component of the underlying sacrificial coating, such as acrosslinker, which may be a chain extender, which may be included as acomponent of the sacrificial coating composition or deposited in/on asacrificial coating, such as a partially dried sacrificial coating. Theink composition may also include a colorant and a solvent.

The ink of the present embodiments may include a latex emulsioncomprising polymer particles. For example, the latex emulsion maycomprise a polystyrene copolymer latex. That is, the latex emulsioncomprises polymer particles comprising polystyrene copolymer formed byemulsion polymerization, for example, of styrene, n-butyl acrylate,methacrylic acid, beta-carboxyethylacrylate (beta-CEA) and a surfactant.In other words, the polystyrene copolymer latex comprises (or can bederived from) styrene monomer and one or more co-monomers such as alkylacrylate, alkyl methacrylate, alkyl acrylate-acrylic acid,1,3-diene-acrylic acid, alkyl methacrylateacrylic acid, alkylmethacrylate-alkyl acrylate, alkyl methacrylate-aryl acrylate, arylmethacrylate-alkyl acrylate, alkyl methacrylateacrylic acid. In certainembodiments, the co-monomer is selected from among acrylates,methacrylates and mixtures thereof. In certain embodiments, thecopolymer is comprised of styrene monomer and an alkyl acrylate. In oneembodiment, the copolymer is comprised of styrene monomer and butylacrylate, e.g., n-butyl acrylate, monomer. In further embodiments, thecopolymer further includes an amount of 13-carboxyethyl acrylate(13-CEA). In certain embodiments, the polystyrene copolymer latexincludes an acrylic emulsion latex, obtained from alkyl acrylates havingalkyl groups of from 1 to 18 carbon atoms, from 1 to 6 carbon atoms, orfrom 1 to 4 carbon atoms. The latex of the latex emulsion may have a lowglass transition temperature (Tg), for example, having a Tg less than63° C., for example, having a Tg of about 53° C. or less.

The reactive elastomeric latex may include a polyurethane elastomer, forexample, the water-based aliphatic polyurethane elastomer described foruse in the sacrificial coating composition. The reactive elastomericlatex may be provided in an amount, for example, from greater than 0 wt% to about 10 wt %, such as from about 0.01 wt % to about 10 wt %, suchas greater than 0 wt % and less than about 5 wt % of the inkcomposition.

The ink composition may have a viscosity of about 3 cps to about 12 cpsat a temperature suitable for ejecting as droplets from an inkjetprinthead.

Suitable colorants for use in the ink according to the presentdisclosure include, without limitation, carbon black, lamp black, ironblack, ultramarine, Aniline Black, Aniline Blue, azo oil black, Basic 6GLake, Benzidine Yellow, Benzimidazolone Brown HFR, BenzimidazoloneCarmine HF3C, Brilliant Green lakes, carbon black, Chrome Yellow,Dioxazine Violet, disazo pigments, Disazo Yellow AAA, Du Pont Oil Red,Fast Yellow G, Hansa Brilliant Yellow 5GX, Hansa Yellow, Hansa Yellow G,Lake Red C, Malachite Green hexylate, Malachite Green, metallic salts ofsalicylic acid and salicylic acid derivatives, Methyl Violet Lake,Methylene Blue Chloride Methylene Blue, monoazo pigments, Naphthol RedHFG, Naphtol Yellow, Nigrosine dye, oil black, Phthalocyanine Blue,Phthalocyanine Green, quinacridone, Quinoline Yellow; Rhodamine 6G Lake,Rhodamine B; Rose Bengale, Tartrazine Lake, tertiary ammonium salts,titanium oxide, trisazo pigments, Ultramarine Blue, Victoria Blue,Watching Red, mixtures thereof, and the like.

An indirect printing process that utilizes the sacrificial coatingcomposition and ink compositions above is performed by way of an inkimage producing machine, such as a printer. FIG. 1 illustrates ahigh-speed aqueous ink image producing machine or printer 10. Asillustrated, the printer 10 is an indirect printer that forms an inkimage on a surface of a blanket 21 mounted about an intermediaterotating member 12 and then transfers the ink image to media passingthrough a nip 18 formed between the blanket 21 and the transfix roller19. The surface 14 of the blanket 21 is referred to as the imagereceiving surface of the blanket 21 and the rotating member 12 becausethe surface 14 receives a hydrophilic composition and the aqueous inkimages that are transfixed to print media during a printing process.

A print cycle is now described with reference to the printer 10. As usedin this document, “print cycle” refers to the operations of a printer toprepare an imaging surface for printing, ejection of the ink onto theprepared surface, treatment of the ink on the imaging surface tostabilize and prepare the image for transfer to media, and transfer ofthe image from the imaging surface to the media, including an indirectprinting process of the embodiments.

The printer 10 includes a frame 11 that supports directly or indirectlyoperating subsystems and components, which are described below. Theprinter 10 includes an intermediate transfer member, which isillustrated as rotating imaging drum 12 in FIG. 1, but can also beconfigured as a supported endless belt. The imaging drum 12 has an outerblanket 21 mounted about the circumference of the drum 12. The blanketmoves in a direction 16 as the member 12 rotates. A transfix roller 19rotatable in the direction 17 is loaded against the surface of blanket21 to form a transfix nip 18, within which ink images formed on thesurface of blanket 21 are transfixed onto a print medium 49. In someembodiments, a heater in the drum 12 (not shown) or in another locationof the printer heats the image receiving surface 14 on the blanket 21 toa temperature in a range of, for example, approximately 50° C. toapproximately 70° C. The elevated temperature promotes partial drying ofthe liquid carrier that is used to deposit the sacrificial coatingcomposition and of the water in the aqueous ink drops that are depositedon the image receiving surface 14.

The blanket is formed of a material, such as that described above,having a relatively low surface energy to facilitate transfer of the inkimage from the surface of the blanket 21 to the print medium 49 in thenip 18. Such materials include polysiloxanes, fluoro-silicones,fluoropolymers such as VITON or TEFLON and the like. A surfacemaintenance unit (SMU) 92, described below, removes residual ink left onthe surface of the blanket 21 after the ink images are transferred tothe print medium 49. The low energy surface of the blanket does not aidin the formation of good quality ink images because such surfaces do notspread ink drops as well as high energy surfaces.

In an embodiment depicted in FIG. 2A, the SMU 92 includes a coatingapplicator, such as a donor roller 404, which is partially submerged ina reservoir 408 that holds one or more components of the sacrificialcoating composition described above. For example, reservoir 408 may holdsome or all of the following: the at least one polymer, the at least oneof (i) the at least one crosslinker, for example, a chain extender, or(ii) the reactive elastomeric latex, the at least one hygroscopicplasticizer, and the at least one surfactant. During operation of theprinter 10, the donor roller 404 rotates in response to the movement ofthe image receiving surface 14 in the process direction. The donorroller 404 draws the liquid sacrificial coating composition from thereservoir 408 and deposits a layer (not visible) of the composition onthe image receiving surface 14. The sacrificial coating composition maybe deposited as a uniform layer having any desired thickness. Examplesinclude thicknesses ranging from about 0.1 μm to about 10 μm. The SMU 92deposits the sacrificial coating composition on the image receivingsurface 14. After a drying process, the dried sacrificial coatingsubstantially covers the image receiving surface 14 before the printerejects ink drops during a print process. In some embodiments, the donorroller 404 is an anilox roller or an elastomeric roller made of amaterial, such as rubber.

In an embodiment depicted in FIG. 2B, the SMU 92 includes a more thanone of a sacrificial coating applicator, such as a donor roller 404′ andat least one printhead 404″. Donor roller 404′ is partially submerged ina reservoir 408′ that holds one or more components of the sacrificialcoating composition. For example the reservoir 408′ holds a firstportion of the liquid sacrificial coating composition described above.The first portion of the liquid sacrificial may include the at least onepolymer, the at least one hygroscopic plasticizer, and the at least onesurfactant. The donor roller 404′ rotates in response to the movement ofthe image receiving surface 14 in the process direction. The donorroller 404′ draws the first portion of the liquid sacrificial coatingcomposition from the reservoir 408″ and deposits (not visible) a layerof the first portion of the sacrificial coating composition on the imagereceiving surface 14. The sacrificial coating composition may bedeposited as a uniform layer having any desired thickness. Examplesinclude thicknesses ranging from about 0.1 μm to about 10 μm. In someillustrative embodiments, the donor roller 404′ is an anilox roller oran elastomeric roller made of a material, such as rubber.

The at least one printhead 404″ includes a sacrificial coatingcomposition supply and delivery subsystem 91 (shown in FIG. 1) that hasat least one source 93 (also shown in FIG. 1) to provide a secondportion of the sacrificial coating composition. The second portion ofthe sacrificial coating composition may include the at least onecrosslinker, which may be a chain extender. Printhead 404″ extendsacross the width of the blanket and ejects droplets 408″ of the secondportion of the sacrificial coating composition onto the first portion ofthe sacrificial coating composition deposited by roller 404′ in, forexample, an imagewise pattern. The at least one printhead 404″ can beincluded in a printhead module that includes a single printhead or aplurality of printheads, for example, a plurality of printheadsconfigured in a staggered arrangement for delivery of the droplets ofthe second portion of sacrificial coating composition. The printheadmodule can be operatively connected to a frame (not shown) and alignedto eject the droplets of the second portion of the sacrificial coatingcomposition in an imagewise pattern 412 on the first portion of thesacrificial coating composition deposited by roller 404′. The associatedprinthead module for the at least one printhead 404″ can includecorresponding electronics, reservoirs, and conduits to supply the secondportion of the sacrificial coating composition to the one or moreprintheads. For example, conduits (not shown) can operatively connect asource 93 (shown in FIG. 1) to the at least one printhead 404″ toprovide a supply of sacrificial coating composition, for example, thesecond portion of the sacrificial coating composition, to the at leastone printhead 404″. The at least one printhead 404″ can be the same kindof printhead used for depositing ink, such as printheads associated withprinthead modules 34A-34D described below. The printhead for jetting thesacrificial coating composition can be a conventional printhead such asKyocera KJ4B series which is designed for jetting water based inks. Insome embodiments, SMU does not include roller 404′ and the first andsecond portions of the sacrificial coating composition are eachdeposited by respective ones of the at least one printhead 404″. In someembodiments, a combination of roller 404′ and more than one printhead404″ may each be utilized to deposit different or same components of thesacrificial coating composition.

At least the second portion of the sacrificial coating composition, forexample, the crosslinker, which may be a chain extender, can bedeposited dropwise, via jetting from a nozzle associated with printhead404″, and in an imagewise pattern. The second portion of sacrificialcoating composition deposited in this manner can have any desiredthickness. Examples include thicknesses ranging from about 0.1 μm toabout 10 μm.

Returning to FIG. 1, the SMU 92 deposits the sacrificial coatingcomposition on the image receiving surface 14. After a drying process,for example, at least a partial-drying process, the dried (or partiallydried) sacrificial coating composition is formed into sacrificialcoating that covers the whole image receiving surface, or only theportion of the image receiving surface 14 defining an image, forexample, where the at least one printheads of printhead modules 34A-34Dsubsequently eject ink drops in an imagewise pattern during a printprocess. Alternatively, after a drying process, for example, at least apartial-drying process, the dried (or partially dried) sacrificialcoating composition, such as the first portion of the sacrificialcoating composition, is formed into sacrificial coating that covers thewhole image receiving surface, with the second portion of thesacrificial coating composition covering a portion of the imagereceiving surface 14 defining an image, for example, where the at leastone printheads of printhead modules 34A-34D subsequently eject ink dropsin an imagewise pattern during a print process.

The SMU 92 can be operatively connected to a controller 80, described inmore detail below, to enable the controller to operate the donor roller,printhead, and a metering blade and a cleaning blade (not visible),selectively to deposit and distribute the sacrificial coatingcomposition onto the surface of the blanket and to remove un-transferredink and any sacrificial coating residue from the surface of the blanket21.

Referring back to FIG. 1, to perform the drying or partial drying,and/or curing or partial curing of the sacrificial coating compositiondeposited by SMU, the printer 10 includes a dryer 96 that emits heat andoptionally directs an air flow toward the sacrificial coatingcomposition that is applied to the image receiving surface 14. The dryer96 facilitates the evaporation of at least a portion of the liquidcarrier from the sacrificial coating composition to leave a dried layeron the image receiving surface 14 before the intermediate transfermember passes the printhead modules 34A-34D to receive the aqueousprinted image. For example, dryer 96 may partially dry the sacrificialcoating composition, such as the first portion and/or section portion ofthe sacrificial coating composition, to form a sacrificial coating.Optionally, depending on temperature and time that sacrificial coatingcomposition is exposed to the dryer, the dryer may serve to activate thecrosslinker, such as a chain extender, of the liquid sacrificialcoating, for example, the crosslinker of the second portion of thesacrificial coating composition ejected by the printhead in an imagewisepattern, to at least partially cure the sacrificial coating composition.

The printer 10 can include an optical sensor 94A, also known as animage-on-drum (“IOD”) sensor, which is configured to detect lightreflected from the blanket surface 14 and the sacrificial coatingapplied to the blanket surface as the member 12 rotates past the sensor.The optical sensor 94A includes a linear array of individual opticaldetectors that are arranged in the cross-process direction across theblanket 21. The optical sensor 94A generates digital image datacorresponding to light that is reflected from the blanket surface 14 andthe sacrificial coating. The optical sensor 94A generates a series ofrows of image data, which are referred to as “scan lines,” as theintermediate transfer member 12 rotates the blanket 21 in the direction16 past the optical sensor 94A. In one embodiment, each optical detectorin the optical sensor 94A further comprises three sensing elements thatare sensitive to wavelengths of light corresponding to red, green, andblue (RGB) reflected light colors. Alternatively, the optical sensor 94Aincludes illumination sources that shine red, green, and blue light or,in another embodiment, the sensor 94A has an illumination source thatshines white light onto the surface of blanket 21 and white lightdetectors are used. The optical sensor 94A shines complementary colorsof light onto the image receiving surface to enable detection ofdifferent ink colors using the photodetectors. The image data generatedby the optical sensor 94A can be analyzed by the controller 80 or otherprocessor in the printer 10 to identify the thickness of the sacrificialcoating on the blanket and the area coverage. The thickness and coveragecan be identified from either specular or diffuse light reflection fromthe blanket surface and/or coating. Other optical sensors, such as 94B,94C, and 94D, are similarly configured and can be located in differentlocations around the blanket 21 to identify and evaluate otherparameters in the printing process, such as missing or inoperativeinkjets and ink image formation prior to image drying (94B), ink imagetreatment for image transfer (94C), and the efficiency of the ink imagetransfer (94D). Alternatively, some embodiments can include an opticalsensor to generate additional data that can be used for evaluation ofthe image quality on the media (94E).

The printer 10 includes an airflow management system 100, whichgenerates and controls a flow of air through the print zone. The airflowmanagement system 100 includes a printhead air supply 104 and aprinthead air return 108. The printhead air supply 104 and return 108are operatively connected to the controller 80 or some other processorin the printer 10 to enable the controller to manage the air flowingthrough the print zone. This regulation of the air flow can be throughthe print zone as a whole or about one or more printhead arrays. Theregulation of the air flow helps prevent evaporated solvents and waterin the ink from condensing on the printhead and helps attenuate heat inthe print zone to reduce the likelihood that ink dries in the inkjets,which can clog the inkjets. The airflow management system 100 can alsoinclude sensors to detect humidity and temperature in the print zone toenable more precise control of the temperature, flow, and humidity ofthe air supply 104 and return 108 to ensure optimum conditions withinthe print zone. Controller 80 or some other processor in the printer 10can also enable control of the system 100 with reference to ink coveragein an image area or even to time the operation of the system 100 so aironly flows through the print zone when an image is not being printed.

The high-speed aqueous ink printer 10 also includes an aqueous inksupply and delivery subsystem 20 that has at least one source 22 of onecolor of aqueous ink, for example, an ink composition comprising thelatex emulsion, reactive elastomeric latex, at least one colorant and atleast one solvent comprising water as discussed above. Since theillustrated printer 10 is a multicolor image producing machine, the inkdelivery system 20 includes, for example, four (4) sources 22, 24, 26,28, representing four (4) different colors CYMK (cyan, yellow, magenta,black) of aqueous inks. In the embodiment of FIG. 1, the printheadsystem 30 includes a printhead support 32, which provides support for aplurality of printhead modules, also known as print box units, 34Athrough 34D. Each printhead module 34A-34D effectively extends acrossthe width of the blanket and ejects ink drops onto the surface 14 of theblanket 21. A printhead module can include a single printhead or aplurality of printheads configured in a staggered arrangement. Eachprinthead module is operatively connected to a frame (not shown) andaligned to eject the ink drops to form an ink image on the coating onthe blanket surface 14. The printhead modules 34A-34D can includeassociated electronics, ink reservoirs, and ink conduits to supply inkto the one or more printheads. In the illustrated embodiment, conduits(not shown) operatively connect the sources 22, 24, 26, and 28 to theprinthead modules 34A-34D to provide a supply of ink to the one or moreprintheads in the modules. As is generally familiar, each of the one ormore printheads in a printhead module can eject a single color of ink.In other embodiments, the printheads can be configured to eject two ormore colors of ink. For example, printheads in modules 34A and 34B caneject cyan and magenta ink, while printheads in modules 34C and 34D caneject yellow and black ink. The printheads in the illustrated modulesare arranged in two arrays that are offset, or staggered, with respectto one another to increase the resolution of each color separationprinted by a module. Such an arrangement enables printing at twice theresolution of a printing system only having a single array of printheadsthat eject only one color of ink. Although the printer 10 includes fourprinthead modules 34A-34D, each of which has two arrays of printheads,alternative configurations include a different number of printheadmodules or arrays within a module.

Accordingly, during operation of printer 10, in which the printerperforms an indirect printing process, the printheads of modules 34A-34Dmay eject droplets of an ink composition in the imagewise pattern ontothe dried or partially dried, cured or partially cured sacrificialcoating. Thus, the reactive elastomeric latex of the ink deposited inthe imagewise pattern may react with the crosslinker, such as the chainextender, deposited with all other components of the sacrificialcomposition to cover the whole blanket (such as the SMU shown in FIG.2A), or the crosslinker (or chain extender) deposited in an imagewisepattern as ejected droplets from printhead 404″ of SMU 92 (as shown inFIG. 2B).

After the printed image on the blanket surface 14 exits the print zone,the image passes under an image dryer 130. The image dryer 130 includesa heater, such as a radiant infrared, radiant near infrared and/or aforced hot air convection heater 134, a dryer 136, which is illustratedas a heated air source 136, and air returns 138A and 138B. The infraredheater 134 applies infrared heat to the printed image on the surface 14of the blanket 21 to evaporate water or solvent in the ink. The heatedair source 136 directs heated air over the ink to supplement theevaporation of the water or solvent from the ink. In one embodiment, thedryer 136 is a heated air source with the same design as the dryer 96.While the dryer 96 is positioned along the process direction to dry thehydrophilic composition, the dryer 136 is positioned along the processdirection after the printhead modules 34A-34D to at least partially drythe aqueous ink on the image receiving surface 14. The air is thencollected and evacuated by air returns 138A and 138B to reduce theinterference of the air flow with other components in the printing area.

As further shown, the printer 10 includes a print medium supply andhandling system 40 that stores, for example, one or more stacks of paperprint mediums of various sizes. The print medium supply and handlingsystem 40, for example, includes sheet or substrate supply sources 42,44, 46, and 48. In the embodiment of printer 10, the supply source 48 isa high capacity paper supply or feeder for storing and supplying imagereceiving substrates in the form of cut print mediums 49, for example.The print medium supply and handling system 40 also includes a substratehandling and transport system 50 that has a media pre-conditionerassembly 52 and a media post-conditioner assembly 54. The printer 10includes an optional fusing device 60 to apply additional heat andpressure to the print medium after the print medium passes through thetransfix nip 18. In the embodiment of FIG. 1, the printer 10 includes anoriginal document feeder 70 that has a document holding tray 72,document sheet feeding and retrieval devices 74, and a document exposureand scanning system 76.

Operation and control of the various subsystems, components andfunctions of the machine or printer 10 are performed with the aid of thecontroller 80, such as an electronic subsystem (ESS). The ESS orcontroller 80 is operably connected to the intermediate transfer member12, the printhead modules 34A-34D (and thus the printheads), thesubstrate supply and handling system 40, the substrate handling andtransport system 50, and, in some embodiments, the one or more opticalsensors 94A-94E. The ESS or controller 80, for example, is aself-contained, dedicated mini-computer having a central processor unit(CPU) 82 with electronic storage 84, and a display or user interface(UI) 86. The ESS or controller 80, for example, includes a sensor inputand control circuit 88 as well as a pixel placement and control circuit89. In addition, the CPU 82 reads, captures, prepares and manages theimage data flow between image input sources, such as the scanning system76, or an online or a work station connection 90, and the printheadmodules 34A-34D. As such, the ESS or controller 80 is the mainmulti-tasking processor for operating and controlling all of the othermachine subsystems and functions, including the printing processdiscussed below.

The controller 80 can be implemented with general or specializedprogrammable processors that execute programmed instructions. Theinstructions and data required to perform the programmed functions canbe stored in memory associated with the processors or controllers. Theprocessors, their memories, and interface circuitry configure thecontrollers to perform the operations described below. These componentscan be provided on a printed circuit card or provided as a circuit in anapplication specific integrated circuit (ASIC). Each of the circuits canbe implemented with a separate processor or multiple circuits can beimplemented on the same processor. Alternatively, the circuits can beimplemented with discrete components or circuits provided in very largescale integrated (VLSI) circuits. Also, the circuits described hereincan be implemented with a combination of processors, ASICs, discretecomponents, or VLSI circuits.

Although the printer 10 in FIG. 1 is described as having a blanket 21mounted about an intermediate rotating member 12, other configurationsof an image receiving surface can be used. For example, the intermediaterotating member can have a surface integrated into its circumferencethat enables an aqueous ink image to be formed on the surface.Alternatively, a blanket is configured as an endless rotating belt forformation of an aqueous image. Other variations of these structures canbe configured for this purpose. As used in this document, the term“intermediate imaging surface” includes these various configurations.

Once an image or images have been formed on the blanket and sacrificialcoating under control of the controller 80, the illustrated inkjetprinter 10 operates components within the printer to perform a processfor transferring and fixing the image or images from the blanket surface14 to media. In the printer 10, the controller 80 operates actuators todrive one or more of the rollers 64 in the media transport system 50 tomove the print medium 49 in the process direction P to a positionadjacent the transfix roller 19 and then through the transfix nip 18between the transfix roller 19 and the blanket 21. The transfix roller19 applies pressure against the back side of the print medium 49 inorder to press the front side of the print medium 49 against the blanket21 and the intermediate transfer member 12. Although the transfix roller19 can also be heated, in the exemplary embodiment of FIG. 1, thetransfix roller 19 is unheated. Instead, the pre-heater assembly 52 forthe print medium 49 is provided in the media path leading to the nip.The pre-conditioner assembly 52 conditions the print medium 49 to apredetermined temperature that aids in the transferring of the image tothe media, thus simplifying the design of the transfix roller. Thepressure produced by the transfix roller 19 on the back side of theheated print medium 49 facilitates the transfixing (transfer and fusing)of the image from the intermediate transfer member 12 onto the printmedium 49. The rotation or rolling of both the intermediate transfermember 12 and transfix roller 19 not only transfixes the images onto theprint medium 49, but also assists in transporting the print medium 49through the nip. The intermediate transfer member 12 continues to rotateto enable the printing process to be repeated.

After the intermediate transfer member moves through the transfix nip18, the image receiving surface passes a cleaning unit that removesresidual portions of the sacrificial coating and small amounts ofresidual ink from the image receiving surface 14. In the printer 10, thecleaning unit is embodied as a cleaning blade 95 that engages the imagereceiving surface 14. The blade 95 is formed from a material that wipesthe image receiving surface 14 without causing damage to the blanket 21.For example, the cleaning blade 95 is formed from a flexible polymermaterial in the printer 10. As depicted below in FIG. 1, anotherembodiment has a cleaning unit that includes a roller or other memberthat applies a mixture of water and detergent to remove residualmaterials from the image receiving surface 14 after the intermediatetransfer member moves through the transfix nip 18. As used herein, theterm “detergent” or cleaning agent refers to any surfactant, solvent, orother chemical compound that is suitable for removing any sacrificialcoating and any residual ink that may remain on the image receivingsurface from the image receiving surface. One example of a suitabledetergent is sodium stearate, which is a compound commonly used in soap.Another example is IPA, which is common solvent that is very effectiveto remove ink residues from the image receiving surface. In anembodiment, no residue of the sacrificial coating layer remains on theITM after transferring the ink and sacrificial layer, in which casecleaning of the ITM to remove residual sacrificial coating may not be anissue.

FIG. 3A depicts an indirect printing process 700 for operating anindirect inkjet printer, such as the inkjet printer 10 of FIG. 1. Theprocess 700 is described in conjunction with FIG. 1 showing the printer10, and FIG. 4A-FIG. 4E showing the blanket and coatings, forillustrative purposes. In the discussion below, a reference to theprocess 700 performing an action or function refers to a controller,such as the controller 80 in the printer 10, executing stored programmedinstructions to perform the action or function in conjunction with othercomponents of the printer. The process 700 may be utilized in using asacrificial coating composition, such as that described above, to form acoating, such as a dry/partially dry and/or cured/partially curedsacrificial coating on an image receiving surface of an intermediatetransfer member prior to ejecting liquid ink drops onto the dried layer.The sacrificial coatings and processes of employing these coatings arenot limited to use with printer 10, but can potentially be employed withany inkjet printer comprising an intermediate transfer member, as wouldbe readily understood by one of ordinary skill in the art. Additionally,the sacrificial coating composition may have a pH in the range of about5 pH to about 10 pH. It is noted that a viscosity of the partially driedsacrificial composition may be at least 10 to 100 times greater than aviscosity of the ink composition deposited thereon.

Process 700 begins as the printer forms a liquid sacrificial coatingcomposition layer by applying a layer of a sacrificial coatingcomposition with, for example, a liquid carrier, to the image receivingsurface of the intermediate transfer member (block 704 in FIG. 3A).Alternatively, process 700 may begin at block 704′, of FIG. 3B, whichmay be substituted in for block 704 of FIG. 3A, as the printer forms aliquid sacrificial coating composition layer by applying (at block 705)a first portion of the sacrificial coating composition on theintermediate transfer member and then ejecting a second portion of thesacrificial coating composition, such as a catalyst or crosslinker, ontothe first portion of the sacrificial coating composition (at block 707).With respect to the sacrificial coating compositions of blocks 704 and704′, the liquid carrier may be water or another liquid, such asalcohol, which may be completely or partially evaporated from the imagereceiving surface in order to form a dry or partially dry sacrificialcoating layer, respectively, on the image receiving surface, such as theblanket.

With respect to forming a liquid sacrificial coating composition layer,one or more components of a sacrificial coating composition can beapplied onto an intermediate transfer member of a printing apparatus,such as the printer 10 of FIG. 1. For example, the one or morecomponents of the sacrificial coating composition applied to form thesacrificial coating composition layer may include the at least onepolymer, the at least one of (i) the at least one crosslinker, such as achain extender, or (ii) the reactive elastomeric latex, the at least onehygroscopic plasticizer, and the at least one surfactant as describedabove. Thus block 704 may be performed using the SMU of FIG. 2A in whichall the components of the sacrificial coating composition are depositedonto the surface of the intermediate transfer member by roller 404.Alternatively, block 704′ may be performed using the SMU of FIG. 2B inwhich the first portion of the sacrificial coating composition, whichmay include the at least one hygroscopic plasticizer, the at least onesurfactant and the at least one polymer, is applied at block 705 by theroller 404′. Additionally, the second portion of the sacrificial coatingcomposition may include the at least one crosslinker and may be ejectedas droplets at block 707 onto the first portion of the sacrificialcoating composition applied at block 705, and in an imagewise patternthrough the nozzles of printhead 404″.

Referring to the printer 10 illustrated in FIG. 1, the drum 12 andblanket 21 move in the process direction along the indicated circulardirection 16 during the process 700 to receive the sacrificial coatingcomposition. In FIG. 4A, the surface of the intermediate transfer member504 is covered with the sacrificial coating composition to formsacrificial coating composition layer 508. The SMU depicted in FIG. 2Amay deposit the sacrificial coating composition layer 508 on theintermediate transfer member 504 which may be, for example, the imagereceiving surface 14 of the blanket 21, to form a uniform sacrificialcoating. A greater coating thickness of the sacrificial coatingcomposition enables formation of a uniform layer that completely coversthe image receiving surface, but the increased volume of liquid carrierin the thicker coating requires additional drying time or larger dryersto remove the liquid carrier to form a dried layer. Thinner coatings ofthe sacrificial coating composition require the removal of a smallervolume of the liquid carrier to form the dried layer, but if thesacrificial coating is too thin, then the coating may not fully coverthe image receiving surface. In certain embodiments the sacrificialcoating composition with the liquid carrier is applied at a thickness ofbetween approximately 1 μm and 10 μm. Alternatively, the SMU depicted inFIG. 2B may deposit the sacrificial coating composition layer 508 in twosteps, with the first step being that some of the components of thesacrificial coating composition may be deposited onto transfer member504 as a first portion of layer 508 and others of the components of thesacrificial composition, for example a crosslinker, may be deposited asa second portion of layer 508 (not shown) on the first portion. Thesecond portion may, therefore, be deposited in an imagewise pattern onlyat locations where a subsequently deposited ink composition, such as anink composition that comprises a reactive elastomeric latex capable ofreacting with the crosslinker, is deposited thereon.

Process 700 continues as a dryer in the printer, such as dryer 96 ofFIG. 1, dries or partially dries the sacrificial coating composition toremove at least a portion of the liquid carrier and to form a driedlayer on the image receiving surface (block 708). In the printer 10 thedryer 96 applies radiant heat and optionally includes a fan to circulateair onto the image receiving surface of the drum 12 or belt 13. FIG. 4Bdepicts the dried layer 512. The dryer 96 removes a portion of theliquid carrier, which decreases the thickness of the dried layer that isformed on the image receiving surface. In the printer 10 the thicknessof the dried layer 512 can be any suitable desired thickness. Examplethicknesses range from about 0.1 μm to about 3 μm in differentembodiments, and in certain specific embodiments from about 0.1 to about0.5 μm. Optionally, dryer 96 may energize the crosslinker of thesacrificial coating composition to cure or partially cure thesacrificial coating layer.

The dried or partially dried, and/or cured or partially cured,sacrificial coating 512 is also referred to as a “skin” layer. The driedsacrificial coating 512 may have a uniform thickness that coverssubstantially all of the portion of the image receiving surface. In thecase where the sacrificial coating composition layer is deposited in afirst step and a second step, the portion of the sacrificial coatingcomposition layer deposited in the first step may cover substantiallyall of the portion of the image receiving surface and the portion of thesacrificial coating composition layer that, for example, may include thecrosslinker may cover only the surface of the image receiving surfacethat receives aqueous ink during a printing process, for example, onlythose surfaces covered by the imagewise pattern. As described above,while the sacrificial coating with the liquid carrier includessolutions, suspension, or dispersion of the sacrificial coating materialin a liquid carrier, the dried sacrificial coating 512 covers the imagereceiving surface of intermediate transfer member 504. The driedsacrificial coating 512 has a comparatively high level of adhesion tothe image receiving surface of intermediate transfer member 504, and acomparatively low level of adhesion to a print medium that contacts thedried layer 512. As described in more detail below, when aqueous inkdrops are ejected onto portions of the dried coating 512, such as in animagewise pattern, a portion of the water and other solvents in theaqueous ink permeates the dried coating 512 and the reactive elastomericlatex of the ink reacts with the crosslinker of the dried sacrificialcoating 512.

Process 700 continues as the image receiving surface with the dry orpartially dry and/or cured or partially cured sacrificial coating movespast one or more printheads that eject aqueous ink drops onto thesacrificial coating formed on the intermediate transfer member to form alatent aqueous printed image (block 712). For example, the printheadmodules 34A-34D in the printer 10 eject ink drops in the CMYK colors,for example, in an imagewise pattern to form an ink pattern such as theprinted image. The inks can include an ink composition described above.For example, the inks can include a latex emulsion and a reactiveelastomer latex capable of reacting with the crosslinker (of thesacrificial coating composition). Thus, in an embodiment, the reactiveelastomeric latex may include about 0.01 wt % to about 10 wt % of theaqueous ink composition.

The sacrificial coating 512 may be substantially impermeable to thecolorants in the ink 524, and the colorants may, therefore, remain onthe surface of the dried sacrificial coating 512 where the aqueous inkspreads. The spread of the liquid ink enables neighboring aqueous inkdrops to merge together on the image receiving surface instead ofbeading into individual droplets as occurs in traditional low-surfaceenergy image receiving surfaces.

Referring again to FIG. 3, the process 700 continues with a dryingprocess of the aqueous ink deposited on the dry or partially dry and/orcured or partially cured sacrificial coating formed on the intermediatetransfer member (block 716). The drying process removes a portion, suchas a substantial portion, of the water from the aqueous ink and thesacrificial coating, also referred to as the skin layer, on theintermediate transfer member so that the amount of water that istransferred to a print medium in the printer does not produce cocklingor other deformations of the print medium. Alternatively or in addition,the drying process may be utilized to activate the crosslinker, such asthe chain extender, in the dry or partially dry and/or cured orpartially cured sacrificial coating to crosslink with the reactiveelastomeric latex of the ink.

In the printer 10, the heated air source 136 directs heated air towardthe image receiving surface 14 to dry the printed aqueous ink imageand/or activate the crosslinker to crosslink with the reactive elastomerof the ink. In some embodiments, the intermediate transfer member andblanket are heated to an elevated temperature to promote evaporation ofliquid from the ink and/or from the sacrificial coating compositionlayer. For example, in the printer 10, the imaging drum 12 and blanket21 are heated to a temperature of 50° C. to 70° C. to enable partialdrying of the ink in the dried layer during the printing process. Asdepicted in FIG. 4D, the drying process forms a partially dried aqueousink 532 that retains a reduced amount of water compared to the freshlyprinted aqueous ink image of FIG. 4C and the reactive elastomer of whichmay be crosslinked to the crosslinker of the sacrificial coating 512.

The drying process also increases the viscosity of the aqueous ink,which changes the consistency of the aqueous ink from a low-viscosityliquid to a higher viscosity tacky material. The drying process alsoreduces the thickness of the ink 532. In an embodiment, the dryingprocess removes sufficient water so that the ink contains less that 5%water or other solvent by weight, such as less than 2% water, or evenless than 1% water or other solvent, by weight of the ink.

Process 700 continues as the printer transfixes the latent aqueous inkimage from the image receiving surface to a print medium, such as asheet of paper (block 720). In the printer 10, the image receivingsurface 14 of the drum 12 engages the transfix roller 19 to form a nip18. A print medium, such as a sheet of paper, moves through the nipbetween the drum 12 and the transfix roller 19. The pressure in the niptransfers the latent aqueous ink image and a portion of the dried layerto the print medium. After passing through the transfix nip 18, theprint medium carries the printed aqueous ink image. As depicted in FIG.4E, a print medium 536 carries a printed aqueous ink image 532 with thesacrificial coating 512 covering the ink image 532 on the surface of theprint medium 536. The sacrificial coating 512 provides protection to theaqueous ink image from scratches or other physical damage while theaqueous ink image 532 dries on the print medium 536. The sacrificialcoating 512 may be formed such that it covers the ink image 532 and maynot extend substantially further than the perimeter of the image 532. Inother words, both the ink image and sacrificial coating may each beformed according to an imagewise pattern.

During process 700, the printer cleans any residual portions of thesacrificial coating 512 that may remain on the image receiving surfaceafter the transfixing operation (block 724). In one embodiment, a fluidcleaning system 395 uses, for example, a combination of water and adetergent with mechanical agitation on the image receiving surface toremove the residual portions of the sacrificial coating 512 from thesurface of the belt 13. In the printer 10, a cleaning blade 95, whichcan be used in conjunction with water, engages the blanket 21 to removeany residual sacrificial coating 512 from the image receiving surface14. The cleaning blade 95 is, for example, a polymer blade that wipesresidual portions of the sacrificial coating 512 from the blanket 21.

During a printing operation, process 700 returns to the processingdescribed above with reference to block 704 or 704′ to apply thesacrificial coating composition to the image receiving surface, printadditional aqueous ink images, and transfix the aqueous ink images toprint media for additional printed pages in the print process. Theillustrative embodiment of the printer 10 operates in a “single pass”mode that forms the dried layer, prints the aqueous ink image andtransfixes the aqueous ink image to a print medium in a single rotationor circuit of the intermediate transfer member. In alternativeembodiments, an inkjet employs a multi-pass configuration where theimage receiving surface completes two or more rotations or circuits toform the dried layer and receive the aqueous ink image prior totransfixing the printed image to the print medium.

In some embodiments of the process 700, the printer forms printed imagesusing a single layer of ink such as the ink that is depicted in FIG. 4C.In the printer 10, however, the multiple printhead modules enable theprinter to form printed images with multiple colors of ink formed insingle or stacked layers. In other embodiments of the process 700, theprinter forms images using multiple ink colors. In some regions of theprinted image, multiple colors of ink may overlap in the same area onthe image receiving surface, forming multiple ink layers on thehydrophilic composition layer. The method steps in FIG. 3 can be appliedto the multiple ink layer circumstance with similar results.

EXAMPLES Example 1 Preparation of Emulsion Polymerization Latex

A latex emulsion comprised of polymer particles generated from theemulsion polymerization of styrene, n-butyl acrylate, methacrylic acid,beta-CEA and Dowfax 2A1 surfactant was prepared as follows:

A surfactant solution of 1.7 grams Dowfax 2A1 (anionicalkyldiphenyloxide disulfonate, The Dow Chemical Company) and 236.6grams de-ionized water was prepared by mixing for 10 minutes in astainless steel holding tank. The holding tank was then purged withnitrogen for 5 minutes before transferring into the reactor. The reactorwas then continuously purged with nitrogen while being stirred at 450rpm. The reactor was then heated up to 80° C. at a controlled rate, andheld there.

Separately, 3.6 grams of ammonium persulfate initiator was dissolved in37.7 grams of de-ionized water.

Separately, the monomer emulsion was prepared in the following manner.148.5 g of styrene, 93.5 g of butyl acrylate, 33.0 g methacrylic acid,8.25 g of beta-CEA, 1.7 g of 1-dodecanethiol, 0.96 g of 1,10-decanedioldiacrylate (ADOD) were added to a premix of 9.4 g of Dowfax 2A1 in 126.8g of deionized water were mixed to form an emulsion. 1% of the aboveemulsion (4.22 g) was then slowly dropped into the reactor containingthe aqueous surfactant phase at 80° C. to form the “seeds” while beingpurged with nitrogen. The initiator solution was then slowly chargedinto the reactor.

The monomer emulsion was split into two aliquots, 206.8 g of the monomeremulsion was initially feed into the reactor at 1.67 g/min. The secondaliquot of 213.1 g monomer emulsion was mixed with 2.0 g of DDT andadded to the reactor at 2.37 g/min. Once all the monomer emulsion wascharged into the main reactor, the temperature was held at 80° C. for anadditional 2 hours to complete the reaction. Full cooling was thenapplied and the reactor temperature was reduced to 25° C. The productwas collected into a holding tank and sieved with a 25 μm screen.

The particle size was then measured by Nanotrac® U2275E particle sizeanalyzer to have a D50 of 100.3 nm and a D95 of 141.1 nm. The Tg and Tsresults are summarized in Table 1

TABLE 1 Latex Tg and Ts (softening point) Comparative Latex ExemplaryLatex wt % methacrylic acid (MAA) 12 12 Tg_((on)) (° C.) 63 53 Tssoftening point (° C.) 149 122

Example 2 Base Ink Composition

A small batch of base ink comprising the latex of Example 1 wasprepared. Table 2 summarizes the ink composition:

TABLE 2 Base Ink Composition solution solids wt % mass Component (wt %)(%) (%) (g) Exemplary Latex (of 6.70 39.86 16.81 16.81 Example 1)diethylene glycol 11.55 100 11.55 11.55 1,5-Pentanediol 14.15 100 14.1514.15 Glycerol 4.58 100 4.58 4.58 2-ethyl-1-hexanol 1.00 100 1.00 1.00PEO 0.30 100 0.30 0.30 Carbon Black 300 3.30 14.87 22.19 22.19Triethanolamine 1.00 100 1.00 1.00 anionic 0.01 10 0.1 0.1fluorosurfactant (e.g., S-761P available from ChemGuard SpecialityChemicals, Mansfield Texas) Wetting agent (e.g., 0.1 100 0.1 0.1Surfynol 104H available from Air Products and Chemicals, Inc.,Allentown, PA) Water 57.31 100 28.22 28.22 TOTAL 100.00 100 100.00

Example 3 Reactive Ink Formulation

3 wt % of a reactive latex, for example, a water-based aliphaticpolyurethane elastomer such as PRECIDIUM™ Aqua 90A (available fromQuantum Chemical, Alberta, Canada) was loaded into the base inkformulation of Example 2.

Example 4 Sacrificial Coating Compositions

Three different sacrificial coating compositions, including twoexemplary compositions and a control composition were formulatedaccording to Table 3 below.

TABLE 3 Sacrificial Coatings Compositions SAMPLE Polymer DescriptionComponent Ratio Exemplary Sacrificial 10% Celvol 203 1.5% Celvol 203Coating Composotion PVOH-low Mw, low (PVOH); #1 (includes both partiallyhydrolyzed 5% glycerol; crosslinker and (hydrolysis 87-89%, 1%TERGITOL ™ reactive elastomeric viscosity 3.5-4.5; (TMN-6; availablelatex) pH = 4.5-6.5) from Dow Chemical Company); 3% AQUA 90A (reactiveelastomeric latex); 1% crosslinker; 88.5% DI Water Exemplary Sacrificial10% Celvol 203 1.5% Celvol 203 Coating Composotion PVOH-low Mw, low(PVOH); #2 (includes partially hydrolyzed 5% glycerol; crosslinker butno (hydrolysis 87-89%, 1% TERGITOL ™ reactive elastomeric viscosity3.5-4.5; (TMN-6; available latex) pH = 4.5-6.5) from Dow ChemicalCompany); 1% crosslinker; 91.5% DI Water Control Sacrificial 10% Celvol203 1.5% Celvol 203 Coating Composotion PVOH-low Mw, low (PVOH); (nocrosslinker or partially hydrolyzed 5% glycerol; reactive elastomeric(hydrolysis 87-89%, 1% TERGITOL ™ latex) viscosity 3.5-4.5; (TMN-6;available pH = 4.5-6.5) from Dow Chemical Company); 1% crosslinker;92.5% DI Water

Example 5 Coating Process

Comparative sacrificial coating composition #1, sacrificial coatingcomposition #2, and control sacrificial coating composition of Example 4were each individually coated on corresponding blanket substrates usinga Pamarco anilox roll 165Q13 by hand to form sacrificial coating #1,sacrificial coating #2, and control sacrificial coating, respectively.

The blanket substrates were made from fluorinated polymer G621manufactured by Daikin Industries, Ltd. and a crosslinker, AO700.(aminoethyl aminopropyl trimethoxysilane from Gelest).

A hotplate was set to 60° C. while the substrate temperature was around50° C. The wet film thicknesses of each of the coatings were around 4-5microns and the dry film thickness was around 500 nm to 1.5 microns. Thecoated films were dried in oven at 60° C. for 30 seconds.

Example 6 Optical Microscope Images

FIGS. 5A-5C show optical microscope images taken of each of the coatingsprepared in Example 5 on G621 blanket substrate before a transfer testwas conducted. Very uniform films were achieved for each of the threecompositions of Example 4.

Example 7 Transfer Test

Collins ink, Base Ink (of example 2) and reactive ink (of Example 3)were deposited on the exemplary sacrificial coatings and control coatingof Example 5, and tested at 110° C. to identify optimum condition fortransfer.

The results were graded as “fair,” “pass,” “pass+,” “pass++,” or“pass+++,” based on visual inspection as shown in Table 4 below.

TABLE 4 Transfer properties of Ink Compositions on Sacrificial Coatings.SAMPLE Collins Ink Base Ink Reactive Ink Exemplary Sacrificial fail passNot Tested Coating #1 (formed of composition that included bothcrosslinker and reactive elastomeric latex) Exemplary Sacrificial NotTested pass++ pass+++ Coating #2 (formed of composition that includedcrosslinker but no reactive elastomeric latex) Control Sacrificial NotTested pass+ Not Tested Coating (formed of composition that included nocrosslinker or reactive elastomeric latex)

The results show that a combination of reactive ink composition thatcontains a reactive elastomer and a sacrificial coating formed from asacrificial coating composition that contained a crosslinker that reactswith the reactive elastomer results in a “pass+++” grade because visualinspection revealed significant improvement in transfer efficiency. Thetransferred image was also found to have excellent robustnessproperties.

Notwithstanding that the numerical ranges and parameters setting forththe broad scope of the disclosure are approximations, the numericalvalues set forth in the specific examples are reported as precisely aspossible. Any numerical value, however, inherently contains certainerrors necessarily resulting from the standard deviation found in theirrespective testing measurements. Moreover, all ranges disclosed hereinare to be understood to encompass any and all sub-ranges subsumedtherein.

While the present teachings have been illustrated with respect to one ormore implementations, alterations and/or modifications can be made tothe illustrated examples without departing from the spirit and scope ofthe appended claims. In addition, while a particular feature of thepresent teachings may have been disclosed with respect to only one ofseveral implementations, such feature may be combined with one or moreother features of the other implementations as may be desired andadvantageous for any given or particular function. Furthermore, to theextent that the terms “including,” “includes,” “having,” “has,” “with,”or variants thereof are used in either the detailed description and theclaims, such terms are intended to be inclusive in a manner similar tothe term “comprising.” Further, in the discussion and claims herein, theterm “about” indicates that the value listed may be somewhat altered, aslong as the alteration does not result in nonconformance of the processor structure to the illustrated embodiment. Finally, “exemplary”indicates the description is used as an example, rather than implyingthat it is an ideal.

It will be appreciated that variants of the above-disclosed and otherfeatures and functions, or alternatives thereof, may be combined intomany other different systems or applications. Various presentlyunforeseen or unanticipated alternatives, modifications, variations, orimprovements therein may be subsequently made by those skilled in theart which are also intended to be encompasses by the following claims.

What is claimed is:
 1. An aqueous sacrificial coating composition for animage transfer member in an aqueous ink imaging system, comprising: atleast one polymer, at least one selected from (i) at least one chainextender, or (ii) a reactive elastomeric latex, wherein the at least onechain extender comprises a species capable of linking linear chains orchain segments of the reactive elastomeric latex; at least onehygroscopic plasticizer; at least one surfactant.
 2. The aqueoussacrificial coating composition of claim 1, wherein the at least onepolymer comprises at least one hydrophilic polymer selected from thegroup consisting of starch, polyvinyl alcohol (PVOH), copolymers ofPVOH, poly(vinylpyrrolidinone) (PVP), poly(ethylene oxide), hydroxyethylcellulose, cellulose acetate, poly(ethylene glycol), poly(ethyleneglycol), copolymers of poly(ethylene glycol), diblock copolymers ofpoly(ethylene glycol), triblock copolymers of poly(ethylene glycol),polyacrylamide (PAM), poly(N-isopropylacrylamide) (PNIPAM), poly(acrylicacid), polymethacrylate, acrylic polymers, maleic anhydride copolymers,sulfonated polyesters, and mixtures thereof.
 3. The aqueous sacrificialcoating composition of claim 1, wherein the at least one polymercomprises one or more repeating polymeric units selected from the groupconsisting of alkyl acrylate, styrene and butadiene, isoprene,methacrylonitrile, acrylonitrile, vinyl ethers, vinyl esters, vinylketones, vinylidene halide, N-vinyl indole, N-vinyl pyrrolidene, acrylicacid, methacrylic acid, acrylamide, methacrylamide, vinylpyridine,vinylpyrrolidone, vinyl-N-methylpyridinium chloride, vinyl naphthalene,p-chlorostyrene, vinyl chloride, vinyl bromide, vinyl fluoride,ethylene, propylene, butylene, isobutylene, and mixtures thereof.
 4. Theaqueous sacrificial coating composition of claim 1, wherein the at leastone chain extender is selected from the group consisting of ethyleneglycol, diethylene glycol, triethylene glycol, tetraethylene glycol,propylene glycol, dipropylene glycol, tripopylene glycol,1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol,1,6-heanediol, 1,4-cyclohexanedimethanol, hydroquinoneBis(2-hydroxyethyl)ether (HQEE), ethanolamine, diethanolamine,methyldiethanolamine, phenyldiethanolamine, glycerol,trimethylolpropane, 1,2,6-hexanetriol, triethanolamine, pentaerythritol,N,N,N′,N′-tetrakis(2-hdroxypropyl)ethylenediamine,diethyltoluenediamine, dimethylthiotoluenediamine,1,4,-Bis(2-hydroxyethoxy)benzene, or mixtures thereof.
 5. The aqueoussacrificial coating composition of claim 1, wherein the reactiveelastomeric latex comprises a water-based aliphatic polyurethaneelastomer.
 6. The aqueous sacrificial coating composition of claim 1,wherein the at least one hygroscopic plasticizer is selected from thegroup consisting of glycerol, sorbitol, vinyl alcohol such as ethylenevinyl alcohol, propylene glycol, hexylene glycol, butylene glycol,xylitol, maltito, polymeric polyols such as polydextrose, glyceryltriacetate, urea, alpha-hydroxy acids (AHA's), and mixtures thereof. 7.The aqueous sacrificial coating composition of claim 1, wherein thesurfactant comprises at least one of an anionic surfactant, at least oneof a non-ionic surfactant, or mixtures thereof.
 8. The aqueoussacrificial coating composition of claim 1, further comprises a pH ofabout 5 to about
 10. 9. An aqueous ink composition, comprising: a latexemulsion; and a reactive elastomeric latex capable of reacting with achain extender; at least one colorant; and at least one solventcomprising water.
 10. The aqueous ink composition of claim 9, whereinthe latex emulsion comprises polymer particles comprising polystyrenecopolymer formed by emulsion polymerization of styrene, n-butylacrylate, methacrylic acid, beta-carboxyethylacrylate (beta-CEA) and asurfactant.
 11. The aqueous ink composition of claim 9, wherein thelatex emulsion comprises a copolymer comprised of styrene monomer andbutyl acrylate monomer.
 12. The aqueous ink composition of claim 9,wherein the reactive elastomeric latex comprises a water-based aliphaticpolyurethane elastomer.
 13. The aqueous ink composition of claim 9,wherein the reactive elastomeric latex comprises about 0.01 wt % toabout 10 wt % of the aqueous ink composition.
 14. The aqueous inkcomposition of claim 9, further comprising a viscosity of about 3 toabout 12 cps at a temperature suitable for ejecting as droplets from aninkjet printhead.
 15. An indirect printing process, comprising: forminga liquid sacrificial coating composition layer by applying one or morecomponents of a sacrificial coating composition onto an intermediatetransfer member of a printing apparatus, wherein the one or morecomponents are selected from the group consisting of: at least onepolymer, at least one chain extender, wherein the at least one chainextender comprises a species capable of linking linear chains or chainsegments of the reactive elastomeric latex; at least one hygroscopicplasticizer; and at least one surfactant; forming a sacrificial coatingby at least partially drying the liquid sacrificial coating composition;optionally, forming a partially cured sacrificial coating by activatingthe chain extender of the liquid sacrificial coating composition to atleast partially cure the sacrificial coating; ejecting droplets of anink composition in an imagewise pattern onto the partially driedsacrificial coating or partially cured sacrificial coating, wherein theink composition comprises: a latex emulsion; and a reactive elastomericlatex capable of reacting with the chain extender; processing the ink toform an ink pattern on the intermediate transfer member, whereinprocessing comprises activating the chain extender to react with thereactive elastomeric latex and substantially drying the ink composition;and transferring both the ink pattern and the sacrificial coating fromthe intermediate transfer member to a final substrate.
 16. The processof claim 15, wherein the applying one or more components of thesacrificial coating composition comprises: applying a first portion ofthe liquid sacrificial coating composition comprising the at least onehygroscopic plasticizer, the at least one surfactant, and the at leastone polymer onto the intermediate transfer member; and ejecting dropletsof a second portion of the liquid sacrificial coating composition, thesecond portion comprising the at least one chain extender throughnozzles of a printhead onto the first portion of the liquid sacrificialcoating composition layer.
 17. The process of claim 16, wherein thedroplets of the second portion of the liquid sacrificial coatingcomposition comprising the at least one chain extender are ejected inthe imagewise pattern.
 18. The process of claim 15, wherein the chainextender comprises between about 0.1 wt % and about 10 wt % of theliquid sacrificial coating composition.
 19. The process of claim 15,wherein the reactive elastomeric latex comprises about 0.01 wt % toabout 10 wt % of the aqueous ink composition.
 20. The process of claim15, wherein a viscosity of the partially dried sacrificial compositionis at least 10 times greater than a viscosity of the ink composition.